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A fish (pl.: fish or fishes) is an aquatic, anamniotic, gill-bearing vertebrate animal with swimming fins and a hard skull, but lacking limbs with digits. Fish can be grouped into the more basal jawless fish and the more common jawed fish, the latter including all living cartilaginous and bony fish, as well as the extinct placoderms ...
Learn about the diversity, evolution, and ecology of fish, the vertebrates that live in water and have a backbone. Explore stunning photos and videos of different fish species, from sharks and rays to salmon and eels.
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A fish is any of approximately 34,000 species of vertebrate animals. The term fish is applied to a variety of vertebrates of several evolutionary lines. It describes a life-form rather than a taxonomic group.
How do fish sleep?
When a fish sleeps, it exists in a seemingly listless state in which the fish maintains its balance but moves slowly. If attacked or disturbed, most fish can dart away. A few kinds of fish lie on the bottom to sleep. Most fish do not have eyelids, so they cannot close their eyes to sleep.
How do fish hear?
The organs of hearing in fish are entirely internal, located within the skull, on each side of the brain, and somewhat behind the eyes. Sound waves, especially those of low frequencies, travel readily through water and impinge directly upon the bones and fluids of the head and body to be transmitted to the hearing organs.
fish, any of approximately 34,000 species of vertebrate animals (phylum Chordata) found in the fresh and salt waters of the world. Living species range from the primitive jawless lampreys and hagfishes through the cartilaginous sharks, skates, and rays to the abundant and diverse bony fishes. Most fish species are cold-blooded; however, one species, the opah (Lampris guttatus), is warm-blooded.
Fishes have been in existence for more than 450 million years, during which time they have evolved repeatedly to fit into almost every conceivable type of aquatic habitat. In a sense, land vertebrates are simply highly modified fishes: when fishes colonized the land habitat, they became tetrapod (four-legged) land vertebrates. The popular conception of a fish as a slippery, streamlined aquatic animal that possesses fins and breathes by gills applies to many fishes, but far more fishes deviate from that conception than conform to it. For example, the body is elongate in many forms and greatly shortened in others; the body is flattened in some (principally in bottom-dwelling fishes) and laterally compressed in many others; the fins may be elaborately extended, forming intricate shapes, or they may be reduced or even lost; and the positions of the mouth, eyes, nostrils, and gill openings vary widely. Air breathers have appeared in several evolutionary lines.
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Many fishes are cryptically coloured and shaped, closely matching their respective environments; others are among the most brilliantly coloured of all organisms, with a wide range of hues, often of striking intensity, on a single individual. The brilliance of pigments may be enhanced by the surface structure of the fish, so that it almost seems to glow. A number of unrelated fishes have actual light-producing organs. Many fishes are able to alter their coloration—some for the purpose of camouflage, others for the enhancement of behavioral signals.
Learn about fish, the diverse group of vertebrates that live in water and have gills, scales, and fins. Explore the evolution, diversity, ecology, and human uses of fish, from jawless lampreys to warm-blooded opahs.
- Sword Fish. Swordfish are commonly known as broadbills and are the only species in the Xiphiidae family. They are large predatory fish that migrate as the seasons change.
- Atlantic Cod. The Atlantic Cod is part of the Gadidae family and is primarly hunted for food by humans. It is labeled as vulnerable by the ICUN due to over-fishing for human consumption.
- Mackerel. Mackerel is a common name given to the pelagic fish which comes from the Scombridae family. They are found in tropical and temperate seas around the world and live offshore or along the coast.
- Trout. The Rainbow Trout fish is a species of the Salmonid family and lives in the Pacific Ocean in North America and Asia. It prefers the cold water and usually comes back to fresh water to spawn.
- Alaskan salmon. There’s a debate about whether wild salmon or farmed salmon is the better option. Farmed salmon is significantly cheaper, but it may contain less omega-3s and fewer vitamins and minerals, depending on whether it’s fortified or not.
- Cod. This flaky white fish is a great source of phosphorus, niacin, and vitamin B-12. A 3-ounce cooked portion contains 15 to 20 grams of protein. Try a piccata sauce on top of cod for a nice complement, like in this recipe.
- Herring. A fatty fish similar to sardines, herring is especially good smoked. Smoked fish is packed with sodium though, so consume it in moderation. Jamie Oliver’s Mediterranean-style herring linguine uses the fresh version in this recipe.
- Mahi-mahi. A tropical firm fish, mahi-mahi can hold up to almost any preparation. Because it’s also called dolphinfish, it’s sometimes confused with the mammal dolphin.
Jan 3, 2023 · Learn about the diversity, characteristics, evolution, and exceptions of fish, the aquatic vertebrates with gills, fins, and scales. Find out how fish are classified, what they eat, and how they reproduce.
Learn about different types of fish, their habitats, and how they breathe. Explore fun facts and photos of blue marlin, bull shark, clown anemonefish, electric eel, and more.
